The present invention generally relates to data communication and, but not by way of limitation, to adaptive line equalizers or line stretcher to improve analog, digital and radio frequency (RF) transmission over various types of transmission mediums.
In recent years, the need to facilitate communication and interoperability among devices present inside or within the close vicinity of a building has led to the development of Home Area Networking (HAN). In this way, digital devices gain enhanced prominent capabilities which may be used to increase quality of life in variety of ways, such as for example, enhanced home security, providing entertainment services with easier access, full automation of repetitious task, and providing smart houses with fully networked structures.
To achieve full connectivity both wired and wireless technologies may be used in Home Area Networking (HAN). Home networking may use Ethernet cables, cable lines, telephone lines, power lines, fiber optics or any other type of transmission line, and Wi-Fi wireless LAN connections. A cost-effective alternative to wireless networking or installing additional network cable is the use of existing home wiring as a network medium. FIG. 1 depicts an embodiment of a Home Area Networking (HAN) 100 where different household appliances and smart devices, such as for example network printers and handheld mobile computers (i.e., cell phones, tablets, laptops, etc.) are connected to a power line network. This structure allows for remotely accessing and controlling the household appliances through handheld mobile devices which are connected to 3G or 4G Internet.
Most wired network infrastructures found in buildings currently utilize twisted copper-pair or coaxial-based transport system. Other types of conductors may also be used in wired networks. Table I summarizes electrical characteristics (characteristic impedance, shunt capacitance per unit length, series inductance per unit length, propagation delay, inner conductor diameter, outer conductor diameter, velocity, and attenuation per unit length, etc.) for various types of conductors used in wired networks. It should be noted that the electrical characteristics of power line twisted pair cables (4th-6th rows from Table I) and Ethernet differential twisted pair cables (7th-8th rows from Table I) are calculated from twisted pair equation.
TABLE IExamples of Various Conductors and their Electrical CharacteristicsConductornormAtt′ @C′L′ZoTdDiameterSepar.velocity1000 MHzConductorTypepF/mnH/mΩns/mmmmmEr%dB/100 m50Ω Coax cableRG58U101.0252.0 505.166.647.675Ω Coax cableRG59U67.3429.8 755.166.039.493Ω Coax cable RG62A/U145.31252.64.084.028.5Power line33.9655.0138.94.71.542“twisted pair”(phase, neutral)Power line16.11033.72534.11.5101.5“twisted pair”(phase, neutral)Power line9.91680.04114.11.5501.5“twisted pair”(phase, neutral)Ethernet46.9473.3100 at6.7 @0.5612diff. twisted pairf > 100f > 100(diff. Imp.)KHzKHzEthernet600 atdiff. twisted pair 1.5 KHz(diff. Imp.)Shielded Ethernet150about 10diff. twisted pairParallel aerial6.81640.04913.33103001 (air)2-wire
The frequency response of twisted pair cables and power lines in a residential dwelling are shown, respectively, in FIGS. 2-3. As shown in FIG. 2, the useful frequency band for the nominal impedance of a twisted pair cable (500Ω) ranges from about 3 kHz to about 1 MHz. On the other hand, for high speed data communication, the useful frequency bandwidth of power lines with an impedance characteristic of 75Ω ranges from about 4 MHz to about 30 MHz. It is to be understood that the frequency response of the power lines is measured while the power lines are connected to various household appliances.
One of the main challenges with home networking relying on power line communication technology is how to deal with electrical noise which is injected into the system from standard household appliances. Whenever any appliance (i.e., refrigerator, television, HVAC, etc.) is turned on or turned off, it creates some variation or noise in the transmission path that could disrupt data transfer through the wiring. In addition, the transmission path itself may hold a voltage or high current, and may act as a controlled impedance line having one or multiple branches or sub-branches with open or terminated stubs. Moreover, some electrical outlets in the building may be open, with no devices connected to it, or they may have extension cords interconnected to provide power to a device. All the above-mentioned configurations may create or inject noises into the system that can severely disrupt data communications.
In the appended figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label by a dash and a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one the similar components having the same first reference label irrespective of the second reference label.